1. Field of the Invention
The present invention relates to novel copolymers of carboxylic acids and quaternary ammonium compounds, with or without acrylates or methacrylates, other copolymerizable monomers and crosslinkers. The present invention also relates to the use of these copolymers as thickeners or dispersants, in particular in cosmetic compositions, and to cosmetic compositions containing these copolymers.
2. Description of the Related Art
Thickeners or viscosity regulators conventionally used are copolymers of olefinically unsaturated carboxylic acids such as (meth)acrylic acid, maleic acid or maleic anhydride and hydrophobic comonomers such as esters of (meth)acrylic acid with or without small amounts of a crosslinker. Copolymers of this type are described, for example, in EP-A 328 725 (1) and EP-A 435 006 (2). Polymers of this type may occasionally be used as emulsifying components in water/oil mixtures. The polymers exert their thickening action once a considerable part of the acid functionality has been neutralized with a suitable base; they are then in the form of a polyanion.
Polymers of this type have some disadvantages. Since the hydrophobic comonomer is generally insoluble in water, the polymers must often be synthesized in an organic solvent. Solvents of this type are often a health hazard or even toxic. The content of hydrophobic comonomer makes these polymers generally dispersible in water only with difficulty. Furthermore, it is occasionally necessary to use very large amounts of the hydrophobic comonomer. Another disadvantage is that the stability to electrolytes is often low.
Polymers which have a large number of cationic groups are said likewise to be utilizable as thickeners or dispersants. Polymers of this type have a high affinity for the dispersed substances whose surfaces usually have a negative charge. Cationic polymers may therefore frequently have the opposite effect and lead to coalescence of existing dispersions; they are therefore also preferably used as flocculants.
DE-B 11 08 436 (3) describes copolymers of ethylenically unsaturated compounds which are sparingly soluble in water, eg. esters of unsaturated carboxylic acids, and N- or C-vinyl-substituted aromatic compounds which contain a quaternary N atom, eg. N-vinyl-N'-benzyl-imidazolium chloride. The substances are recommended for the finishing of textiles and for producing films and coatings.